Storage

Microsoft iSCSI Software Target 3.3 for Windows Server 2008 R2: iSCSI SAN for the masses

John Joyner explains how a free software package can transform Windows Server 2008 R2 into an iSCSI SAN provider and provide a cheap entry to private clouds with repurposed physical servers.

A new option for server storage entered the market April 4, 2011 when Microsoft made available for free public download a software package that transforms a standard Windows Server 2008 R2 computer into a Windows Storage Server, aka an iSCSI SAN provider. If you own, or purchase, a Windows Server 2008 R2 license, installing this small application turns your computer into a storage area network (SAN) appliance.

How it works (high-level)

Any physical server capable of running the 64-bit Windows 2008 R2 operating system, with at least two network cards, and lots of local storage is a candidate SAN device. Application servers (that will use the shared storage) also need one or more network cards reserved for iSCSI. After installing the Windows Server 2008 R2 operating system on your storage server, install the iSCSI Target software.

On the client computer that will use the shared storage, you enable the iSCSI Initiator, a built-in part of Windows Server 2008, or install the downloadable iSCSI Initiator software on previous Windows versions. Create shared volumes or VHDs on the storage server and present them to the application servers. On the application servers, such as Hyper-V hosts, you configure the iSCSI Initiator with the IP address of the storage server, and after a few clicks you see the disks in Disk Administrator, ready to initialize and format.

In the case of Hyper-V virtual machines (VMs), the VHDs are presented as iSCSI targets to the Hyper-V host servers, one iSCSI target per VHD. See in Figure A how a VHD is stored on the storage server's local D: drive array, and shared as an iSCSI target.

Figure A - Create VHDs on a large volume on the storage server and present them as iSCSI targets to other servers

Applications for the Microsoft iSCSI Target

This is great stuff to ‘build your own' no-cost/low-cost SAN for development/test use, or even a production SAN if deployed thoughtfully on robust hardware. Many companies use and depend on Windows Storage Server 2008 R2 boxes that include the very same iSCSI Target 3.3 software that is now available for free to Windows server owners. What a great way to repurpose physical servers with large local storage, i.e., > 2-TB. Not much RAM is needed; even 2-GB RAM will do the job in a small environment. Microsoft has made their clustering and high-availability technologies that require a SAN much more accessible. Now anyone with a 1-GB network switch and some extra 1-Gbps Ethernet cards can have a fully functional SAN.

Real world test

This week a new development team member needed a Visual Studio VM in the lab. We cloned an existing development VM running Visual Studio 2010, that had been running as a Hyper-V guest with local VHD storage. The cloned VM was mounted in Hyper-V, with the disk (appearing to Hyper-V as a pass-through disk) actually provided by the iSCSI Initiator software on the Hyper-V host computer. A lead developer took delivery of the new VM and prepared the VM for the new user, checking everything out. After he was done, I chatted with him; he was happy with the result. I asked him if he noticed any performance issues and he said none at all-he had no idea the VM was running over 1-GB Ethernet iSCSI rather than local storage!

Cheap entry to private clouds

Consider repurposing physical servers without a lot of local storage as Hyper-V hosts, as long as they have 6-GB or more RAM; they may have a second career as iSCSI SAN-connected host nodes. Server hardware recently retired as part of technology refreshes might be great candidates to form that pre-production test environment you have needed for a while. A natural way to optimize your resources might be to consolidate most of your storage onto a few servers, and make them storage servers. Then consolidate CPU and RAM on other servers, and make them Hyper-V hosts. Voila, the core components of a private cloud.

Disappointment

Hyper-V host backup is not supported. For application-consistent backups of Hyper-V virtual machines, you need to use a backup agent inside the VM (traditional backup). We also noted that mounted iSCSI volumes used by Hyper-V are also not backed up by DPM 2010, and require in-guest backup using a DPM agent or other software (such as Windows Backup to a different volume).

Recommended next readings

About

John Joyner, MCSE, CMSP, MVP Cloud and Datacenter Management, is senior architect at ClearPointe, a cloud provider of systems management services. He is co-author of the "System Center Operations Manager: Unleashed" book series from Sams Publishing, ...

4 comments
cwhitmore
cwhitmore

I work for a non-profit and we have 2008 R2 datacenter. This would fit well into our DPM 2010 backup strategy. If not for the fact that we already have the datacenter license I agree with other's that this would be waste of a Win2008 R2 license considering that you can download FreeNAS and OpenFiler.

david.hunt
david.hunt

I don't see anyone but a one-eyed MS fanboi using this solution, since there's Open Source, supported ,Linux based solutions that can turn a PC into an iSCSI SAN Appliance, managed totally through a browser. As management is via a web browser, admins don't need to know Linux administration. From the perspective of something that would be easy to manage in a small to medium business, an "Appliance" is far easier and more reliable that a "Windows Server" with its attendant administration, security, anti-virus, etc.. to manage. That's before you look at the cost of an R2 license. But then I'd use VMware, not HyperV as a VM host, even if only hosting Windows VMs. It's all about easy maintenance, stability and up-time.

alexwc4
alexwc4

I understand how having iSCSI can help repurpose a server with little storage, but why burn a 2008 R2 license, and server hardware if all you get is the storage? There are dedicated iSCSI arrays out there. It's not like we have old, unused 2008 R2 servers with 15 disks in them lying around.

chriswong
chriswong

The snapshot functionality is limited as well. You can only present read-only clones of iSCSI LUNs. This would be a huge deal if it could present read-write clones of LUNs...